/Engine/Source/Editor/UnrealEd/Public/MouseDeltaTracker.h
Adds delta movement into the tracker.
void AddDelta ( [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) * InViewportClient, [FKey](API\Runtime\InputCore\FKey) InKey, const int32 InDelta, bool InNudge )